Stainless steel product and method



to the production of and tough, and readily lends itself to weaving intobeltas a few months as a maximum, pending upon the United States Patent3,100,729 STAINLESS STEEL PRGDUCT AND li/EETHOD George N. Goller,Towson, Md, assignor to Armco Steel Corporation, Middletown, Ohio, acorporation of Ohio No Drawing. Filed Apr. 27, 1961, tier. No. 105,37815 Claims. (Cl. 148-125) My invention relates to stainless steelproducts such as sheet, strip, rods and wire and to wire belting,particularly the wire belting for Fourdrinier paper-making machines.

One of the objects of the invention is sheet, strip and wire whichfatigue in use and especially to wire which is well suited woven belts,which wire is strong the provision of ing and to brazing in forming thecompleted belt.

Another object is the provision of a woven wire belt which is resistantto wear and abrasion; which is resistant to corrosion; and which isresistant to fatigue under the conditions of vibration, wear, corrosiveattack and the like, all as encountered in actual practical use.

A further object of my invention is the provision of a method for makinga wire belt and to the wire employed therein, in which method there isenjoyed a simplicity of procedure in combination with an assurance of abelt possessing a long and useful life under the many varying conditionsof actual use.

Other objects of my invention in part will be apparent to one readingthis specification and in part more particularly pointed out.

Accordingly, my invention will be seen to reside in the composition ofingredients, in the combination of procedu'ral steps, and in therelation of each of the same to one or more of the others all asdescribed herein and particularly set forth in the claims at the end ofthis specification.

As conducive to a better understanding of my invention, it may be notedthat in the art of paper-making there conventionally is employed aFourdrinier machine with woven wire belting on which paper pulp forprocessing and elimination of moisture. In these machines the wire beltsemployed commonly range up to a width of 350 inches and a length up to180 feet or more. The mesh size of the belts is on the order of some 40to 90 per lineal inch, the particular mesh depending upon the particulartype-of paper to be made. And the Wire size employed in these beltsranges from .005 to .016 inch diameter. As a matter of furtherinformation, the belts weigh anywhere from 400 pounds to 3,000 poundsapiece. And they are "driven at speeds up to 3,000 feet per minute. 7

At present, the Fourdrinier wire warp wire of the grade C Phosphorbronze (92% copper and 8% tin) and cross or shute wires of brass. Thesewarp wires have a tensile strength of about 72,000 p.s.i., a yieldstrength of 50,000 p.s.i., and an elongation in 10 inches which issomewhat better than: 50%.

A belt lasts only fromabou-t days to perhaps as much the life generallydebelts are made with type of paper of operation, and the type ofequipment employed. For example, in making paper board'the Fourdrinierwire belt may last about seven days, for newsprint about seven tofourteen days, and for special papers using slow speed operation theymay last three months. The principal causes of belt failure aremechanical wear and mechanical fatigue.

The known Fourdrinier wire belts are costly, perishable and replaceableonly at substantial loss of machine time.

is particularly resistant to is charged being processed, speed 3,100,729Patented Aug. 13, 1963 1n the operation of the Fourdrinier machine it isnoted that the belt rides over and is in friction with a number ofsuction boxes. These conventionally are made of a hard Wood such asmaple. And it is not infrequently found that particles of silica andchina clay become embedded in the surfaces of the box with which thebelt comes in contact. As a result loss of the metal of the belt becauseof friction, wear and abrasion becomes considerable. A belt thencustomarily is withdrawn from service when the diameter of the warpwires has been reduced by some 40% of the original diameter. Use beyondthis would court the hazard of belt breakage in use and under load, allat great cost in equipment and in machinery shut-down, this coming at abad time; in planned replacement the paper-making machine is shut downover the weekend or even a holiday in order to prevent loss of a workingday.

A further necessity for belt replacement is a failure of the belt as aresult of fatigue, particularly the fatigue of the warp wires of thebelt. Most of these failures occur at the edges of the belt where thereis a certain amount of flapping in high speed belt movement. It isfound, for example, that at a speed of some 2,800 feet per minute afailure occurs after about 630,000 cycles of belt operation.

And where some mechanical damage occurs in use, such as the formation ofdents, wrinkles, or the like, the life of the belt is substantiallylessened because such damaged areas quickly wear through, giving holesin the belt which cannot be repaired. Further use of a belt in suchcondition runs the risk of producing an inferior paper and suddenbreakage with inconvenient and expensive shut-down of the entire machineas well.

In some instances the operational life of the papermaking belt isshortenedas a result of corrosion-fatigue, that is, fatigue compoundedby corrosive attack of. the metal. In those operations where pulp withcorrosive waters is to be encountered it is customary to use a belt madeup of wires which have been tinned or nickelplated. The tinning ornickel-plating of the wires, of course, is doneprior to their beingwoven into belting.

In order to obtain greater belt life under the conditions encountered inuse, the art has tried belts fashioned of Inconel wire (80% nickel, 14%chromium and 6% iron). These shortly failed as a result of fatigue. Aneffort also has been made to employ belts fashioned of stainless steelof different grades. But all of those belts failed to achieve thesuccess hoped for, failure through fatigue occurring within several daysof usage. As a consequence, it is the known Phosphor bronze-brass tionallife as compared to those of the prior art, all at minimum cost inintial investment, assuring freedom from sudden breakage and atsubstantial savings in machine shut-down time. 1

Referring now more particularly to the practice of my 1' invention, Iproved a woven wire belt for a Fourdrinier paper-making machine, thebelt being fashioned of a chromium-nickel stainless steel wire severelyand critically cold-drawn to particular amount and then tempered withina critical range of heat-treatment. In broad terms, the stainless steelwire employed in the warp essentially conof 16% to 18% chromium,

are also had where the warp wire sists of about 16% to 26% chromium,about 6% to 22% nickel, carbon up to about .25%, with remaindersubstantiallyall iron. Where desired, and especially in certainpaper-making applications, the warp wire includes molybdenum, this inthe amount of some 2% to 3%; For other applications the warp wireincludes one or more of titanium and columbium, this in the amounts upto about 8% for the titanium and up to about 1.2% for the columbium. Asrepresentative of the grades of chromiumnickel stainless steel employedare the American Iron and SteelInstitute types Nos. 302 (17% to 19%chromium, 8% to 10% nickel, .08% to .20% carbon, and remainder iron),304 (18% to 20% chromium, 8% to 11% nickel, carbon 0.08% max, andremainder iron), 304L (analysis of 304 except with carbon .03% max), 305(17% to 19% chromium, 10% to 13% nickel, carbon 0.12% max, and remainderiron), I308 (19% to 21% chromium, 10% to 12% nickel, carbon 0.08% max,and remainder iron), 309 (22% to 24% chromium, 12% to 15% nickel, carbon0.20% max, and remainder iron), 310 (24% to 26% chromium-19% to 22%nickel, carbon 0.25% max, and remainder iron), 316 and 316L (16% to 18%chromium, 10% to 14% nickel, 2% to 3% molyb denum, carbon 0.10% max, forthe type 316, and carbon 0.03% max. for the type 316L, and remainderiron), 317 (18% to 20% chromium, 11% to 14% nickel, 3% to 4% molybdenum,carbon 0.10% max, and remainder iron), 321 (17% to 19% chromium, 8% to11% nickel, carbon 0.08% max., titanium a minimum of times the carboncontent, and remainder iron), and the type 347 (17% to 19% chromium, 9%to 12% nickel, carbon 0.08% max., with titanium a minimum of times thecarbon content, and remainder iron).

Of the several grades indicated above, I find best results are achievedwith warp wire essentially consisting 10% to 14% nickel, 2% to 3%molybdenum, carbon 0.03% maximum, and remainder substantially all iron.-It will be understood in this remainder there is included manganese 2%max., silicon 1% max, phosphorus 0.040% max. and sulphur 0.030% max.This is the type 316L. Excellent results is of like analysis butcontent, that is, the max., this being the type 316.

with greater tolerance for carbon carbon content being 0.10%

' Good results are also achieved with wal p wine essentially consistingof 18% to 20% chromium, 8% to 11% nickel, carb0n 0.08% max, with.manganese 2% max., silicon 1% max, phosphorus 0.040% max., sulphur0.030%

max, and remainder iron, this being type 304. And for shute Wiresatisfactory results are had with stainless steel essentially consistingof 17% to 19% 10% nickel, carbon 0.08% max, silicon 1%- chromium, 8% toto 0.20% manganese 2% max, phosphorus 0.040% max, sulphur 0.030% max,and remainder iron, this being type 302. Other grades of stainless steelmay be employed in the shute Wire where desired, although generally itis felt that no benefit is had by employing the more costly grades ofhigher chromium and nickel contents.

In accordance with the teachings of my invention, the warp wires areseverely cold-drawn, this to the extent of a cold reduction exceeding 80%, and generally amounting to a figure exceeding on up to as much as95% reduction in area. The cold-drawn Wire had is about 0.006 to 0.013inch in diameter. The particular wire size: is dependent upon thespecific requirements. In general, however, the cold-drawn Wire rangesbetween the values indicated. The cold-drawn wire has a tensile tialloss in tensile strength, shows a great improvement in ductility. Thus,with the tempering treatment the tensile strengths of 250,000 to 300,000p.s.i. are lowered to some 110,000 to 140,000 p.s.i. The elongation in10 inches, however, is greatly increased, this to a value of some 20 to40 percent. I find that the grain structure of the drasticallycold-drawn and tempered wire is fine and equiaxed, about ASTM size 10 to12.

It is this drastically cold-drawn and tempered wire which is the Warpwire which is woven into belting material. In the belting of myinvention the shute Wire is preferably in the annealed conditionbecause, as suggested above, it is Warp wire rather than shute wirewhich is subjected to greatest Wear and fatigue. Actually, the wovenwire belting appears to be a wire cloth. The mesh size is on the orderof some 40 to mesh to the lineal inch. Most of the'belts for theFourdrinier paperrnaking machine are of 50 to 60 mesh to the linealinch.

As to specific examples of the warp wire of my invention, one analyzesabout 1 7% chromium, 12% nickel, 2% molybdenum, carbon not exceeding.03% max. and remainder substantially all iron. cold-drawn to the extentof 82% reaching a size of 0.0107" in diameter. Another analyzes about18% chromium, 8% nickel, canborl 0.08% to 0.20%, and remaindersubstantially all iron. This example has been cold-drawn to the extentof about 90%, arriving at a diameter of 0.0087. The mechanicalproperties ot the wire of these two examples is given in Tables 1(a) and1(1)) lbelow. Samples of each of these example have been tempered attemperatures ranging from some 1200 F. up to 1900 F. The tre-atmentaccorded the various wire samples, the mechanical properties had and thefatigue performance for the two specific examples are given in theTables I(a) and 1(1)) below.

TABLE I(a) Mechanical Properties and Fatigue Performance for theCold-Drawn and Tempered Wire of 0.0107" Dlameter Percent Avera e Fatl 0Condition cold-drawn 82% U.T. S. .2% Y .S., elongafatigui tes t s Load,

p.s.l. p.s.l. tlon cycles averaged lbs. V m 10" Above only 245, 000 232,000 .4. Ab no. 1 262,000

ovep us mm 10,44 Above plus 1,300 F. 11, 758 2 8 Above lus 1,400 F.11,718 4 0' Above plus 1, 450 F. 11, 651 4 0' Above plus 1,500 F.- 11,749 4 0' Above plus 1,5s0 F. 8,072 a 0' Above plus 1,s00 F. r 8,031 4 0'Above plus 1,700 F. 110, 000 40, 500 33. 0 7,105 4 of Above lus 1,so0 F.5 103, 000 40, 000 so. 0 6,996 a 0 0. Above plus l,900 F. 5 mm.. 100,000 43, 000 36.0 5, 920 5 0 Above plus 1,400 F.44/mln. 122, 000 37. 0Above plus 1,400 F. 9471111111.. 142, 000 2s. 0 10, 550 1 ii "0. 1

l Furnace length 12 it.

This example has been It is noted from Table 1(a) above that severelycolddrawn wire with an ultimate tensile strength of some 245 000 to262,000 p.s.i. is brought to an ultimate tensile strength of some110,000 to 140,000 p.s.i. through tempering, respectively, at 1700 F.for live minutes for the lower tensile figure and 1400 F. for fiveminutes for the higher tensile figure. correspondingly, however, theelongation in 10 inches is brought up to 33% for a strength of 110,000p.s.i. and 18% for the 139,000 p.s.i. figure. The average number ofcycles for the fatigue test ranges from 7,105 for the specific samplewith tensile strength Off 110,000 p.s.i. and elongation of 33%, to 11,-718 for the specific example with tensile strength of 139,- 000 p.s.i.and elongation of 18%. In all cases several fatigue tests were taken andthe figures given are averages for these several tests.

In the fatigue testing the various strands of wire undergoing test aresuspended into vertical position and are wrapped once around a clusterof 4 rolls each of 1 inch diameter, with the diameter of the clusteramounting to 4 inches, the wire being held taut by a weight of 0.4 lb.

And in the tempering treatment I find that excellent results are hadwith short time treatment at substantial temperatures, this permittinguse of a strand furnace for heating the wire at high speed of travel. Inthe last two examples given in Table 1(a) the wire travelledrespectively at 44 feet/min. and 94 feet/min, this through the furnaceof 12 foot length maintained at 1400 F. The duration of treatment thenamounted to about /4 minute and about /s minute, respectively. Goodresults are had even at greater speeds of travel and shonter times oftreatment but in somewhat higher temperatures. example, I find goodresults are achieved in a 12 toot furnace maintained at 1520 F. with awire speed of 118 feet/minute, this giving a time of treatment amountingto of a minute.

In my invention. the time of treatment is very short and thetemperatures are high, for I find than with this combinationrecrystallization is achieved after the'severe oold-reduotion and yet noobjectionable grain growth follows the recrystallization. Apparently,with the tempering treatment the metal fast recovers from the drasticcold-reduction. Then, withthe continued heating, the grains nucleatearound the original grain boundaries where grains meet (triple points).And following this the grains will begin to grow.- In my method thetempering is interrupted in advance of objectionable grain growth. Inthis way I preserve remnants of the coldworking and pick up new grainsto give maximum formability.

TABLE 1(b) Mechanical Properties and Fatigue Performance for the 90% Cod-Drawn and Tempered Wire 0.0087 Inch.

Diameter 0.2% Percent 1 Condition colddrawn U.T.S., Y.S., elonga-Fatigue Load,

(app. 90%) p.s.i. p.s.i. tion cycles lbs.

Above only 319, 000 319, 000

Above plus 1,200 F. 5 min 202,000 202,000 Do 202, 000 202, 000 Aboveplus 1,280 13. 30 min 151, 000 141, 000 Above plus 1,505 F 5 min 150,00002, 500 130---. 146, 000 84, 000 Above plus 1,615 F. 5 1

min 143, 000 75, 000 37 .5 Do 141, 500 79, 000 37 .5 Above plus 1,675 F.

min 147,000 40 .5 14, 480 0 .4 Do 147, 000 77, 500 42 .5 14, 140 0 .4Above plus 1,675

min 143. 000 70, 000 38 .5 12, 380 0 .4 D0 143, 000 70, 500 38 .5 12,760 0 .4 Above plus 1,700 F. 1 r 1 min 146, 000 73, 750 40 .0

For

TABLE I b --Continued 0.2% Percent Condition cold-drawn U.T.S Y.S.,olouga- Fatigue Load,

(app. p.s.i. p.s.i tion cycles lbs.

Above plus 1,700 F. 5

14, 828 0 .4 Do 13, 908 0 .4 Above plus 1,700 F. 5

min. plus pickled... 13.140 0 .4 Do 13, 428 0 .4

134, 500 47, 000 43 .5 7, 608 0 .4 129. 500 50, 500 37 .5 6, 260 0 .4 Do1... 6,016 0.4 Above plus 1,000 F. 5

min 133,. 000 48, 000 43 .5 3, 948 0 .4 Do 133, 000 48, 750 46 .0 4. 7000 .4

As noted from the mechanical properties given in Table 1(1)), theseverely cold-drawn wire with an ultimate tensile strength of 319,000p.s.i. is bound to have a tensile strength on (the order of 150,000p.s.i. with 10 inch elongation of about 26.8% as a result of temperingtreatment at 1510 F. for 5 minutes. With tempering at 1750 F. for 5minutes the ultimate tensile strength is lowered to 140,000 p.s.i. andthe elongation in 10 inches is-inereased to 40.5%. Somewhat greaterelongation, with further lowering of tensile strength, is bad withtempering at 1900 F. for both 2 minutes and 5 minutes, the elongationarnounting to about 43.50% and the ultimate tensile strength about133,000 p.s.i.

The'tatigue performance for the examples, given in Table 1(b) averagesome 11,000 to 14,000 cycles for the examples tempered at 1725 F. and1675 F., respectively. Here it is noted that in the fatugue testing thewires were loaded to theextent of 0.4 lb. except where otherwiseindicated.

The fatigue performance had with the severely colddrawn and temperedstainless steel wire of my invention compares well with the fatigueperformance had with the bronze wire employed in the prior art. Thus,where the steel wire of my invention, as noted above, achieves a valueof some 11,000 cycles in an average of four tests as noted in Table 1(a)and some 11,000 to 15,000 cycles in Table 1(1)), one sample of bronzewire of .008 inch diameter had an average fatigue life of 11,600 cyclesin six tests. And another bronze Wire of .0076 inch had a t fatigue lifeof some 12,120 to 13,128 cycles, both under test conditions. identicalwith those reported in Tables 1(a) and -I(b). i

And the values of tensile strength and yield strength are very much infavor of my severely cold-drawn and tempered stainless steel wire. Forwhile the two bronze wires respectively referred to above had averagetensile strengths of 70,000 p.s.i. and 75,000 p.s.i. with yieldstrengths of about 35,000 p.s.i. and 37,000 p.s.i. the average tensilestrength of my wire is on the order of 110,000 to. 150,000 p.s.i. withyield strengths of 50,000

i to 120,000 p.s.i. The'ductility of the bronze wire substantiallyexceeds that of the severely cold-drawn and tempered wire of myinvention but, as noted above, the ductility of any wire is adequate forthe purpose and the great increase in strength had over that of thebronze .wire of the prior art gives much greater wear and durabili- -tyunder the conditions of use.

In making up a woven wire belt according to my invention, I employ warpknives of about .006 to .013 inch diameter of the character particularlyset forth above, i.e., wire essentially consisting of about 16% to 26%chromium, about 6% to'22% nickel, carbon about .25% mate, with remaindersubstantially all iron (the preferred warp U wire analyzes about 16% to18% chromium, about to 14% nickel, about 2% to 3% molybdenum, carbon notexceeding about .03% max, and remainder substantially all iron), whichwire has been cold-drawn to at least about 80% and then tempered at atemperature of about 1200 to 1750 F., more particularly l400 to 1700- F,and

preferably 1615 to 1750 'F. for types 302 and 304 for example, andpreferably 1400 to 1600 F. for the types 316, 3161. and 305. For theshute wires, i.e., the cross wires, I preferably employ a wire slightlylarger in diameter than for the warp wire, essentially consisting ofabout 17% to 19% chromium, about 10% to 13% nickel, carbon not excedingabout .l2%, and remainder substantially all iron (type 305), this in theannealed condition, -i.e., heated at a temperature of some 1850 to 2050F. and cooled rapidly.

Woven wire belting in accordance with the teachings of my invention instrips up to 350 inches wide and several hundred feet long is readilyfabricated into a belt for Fourdrinier paper-making machines simply bywelding or brazing together the two ends of the strip. For this purposethere conveniently is employed a silver solder as in the prior art asapplied to the Phosphor bronze belts.

Thus it will be seen that I provide in my invention stainless steel wirepossessing the surprising combination of .good Wear resistance with goodresistance to fatigue. Also that I provide a woven wire belt for theFourdrinier paper-making machines which is strong, tough,corrosionresis-tant, as well as resistant to wear, abrasion and fatigueunder the conditions encountered in actual practical paper-makingoperation. The wire and belting of my invention outlast the wire andbelting of the prior art. And substantial savings are had in the cost ofbelts for the Fourdrinier paper-making machines, this in terms ofinitial investment and in terms of maintenance, upkeep and replacement.

While the wire and-belting of my invention is particularly suited to theFourdrinier paper-making machines, it will be understood that the wireand belting are suited to other applications where strength,corrosionvresistance, resistance to wear and abrasion and resistance tofatigue are called into play. For example wires of about .006 to A", oreven to /2" diameter, particularly .006 to A inchdiameter are bad withsevere coldreduction (exceeding 80%) and then tempered at 1200 to 1750-F. Also it is understood that my invention embraces strip as well aswire which is first severely cold-reduced, that is, an amount exceeding80%, and

especially exceeding 85% and on up to about 95%, and then tempered atabout 1200 to 1750 F., particularly 1400 to 1700 F.

Accordingly, it is to be understood that the description of the wire,strip and belt of my invention as given above is ,to be interpreted asillustrative and not as a limitation.

I claim as my invention:

1. In the production of stainless steel of good fatigue, resistance, theart which comprises providing steel not exceeding /2" thickness andessentially consisting of about 16% to 26% chromium, about 6% to 22%nickel,

*carbonup to about .25% maximum, with remainder substantially all iron;cold-reducing the same, without benefit of intermediate anneal in anamount exceeding about 80% and giving a tensile strength of about250,000 p.s.i. or more; and then tempering the same at a temperature ofabout 1-200 to 1750 F. for about to 30 minutes to give an elongation ofabout 20% to 40% with a tensile strength ofabout 110,000 to 140,000p.s.i.

. and fine equiaxed grain structure.

2. in the production of stainless steel wire and strip of about .006 to/2 inch thickness and of good fatigue resistance,"the art whichcomprises providing wire or strip essentially consisting of about 16% to26% chromium, about 6% to 22% nickel, carbon up to about .25 maximum,

with remainder substantially all iron; cold-reducing the same, withoutbenefit of intermediate anneal, in an amount exceeding 85% and giving atensile-strength of about 250,000 p.s.i. or more; and then tempering thesame at a temperature of about 1400 -F. to 1700 for about A to 5 minutesto give an elongation of about 20% to 40% with a tensile strength ofabout 110,000 to 140,000 psi. and line equi-axed grain structure.

3. In the production of stainless steel Wire of about .006 to /8 inchdiameter and of good fatigue resistance, the ant which comprisesproviding wire essentially consisting of about 16% to 26% chromium,about 6% to 22% nickel, carbon up to about .25 maximum, with remaindersubstantially all iron; cold-drawing thesarne, without benefit ofintermediate anneal, to an amount exceeding and up to about 95%; andthen tempering the same at a temperature of about 1200" F. to 1750 F.for about A to 30 minutes, giving a line equi-axed grain structure.

4. In the production of stainless steel wire of about .006 to .013 inchdiameter and of good fatigue resistance, the art which comprisesproviding wire essentially consist ing of about 16% to 18% chromium,about 10% to 14% nickel, about 2% to 3% molybdenum, carbon not exceedingabout 03%, and remainder iron; cold-drawing the same, Without benefit ofintermediate anneal, in an amount exceeding and on up to and temperingthe same at a temperature of about 1400 F. to 1600 F. for a period oftime not exceeding about A minute, giving a fine equi-axed grainstructure.

5. Stainless steelwire and strip of good fatigue resist I ance, saidwire or strip essentially consisting of about 16% 2% to 3% molybdenum,carbon not exceeding about .03 and remainder substantially all iron andhaving a fine equi-axed grain structure.

7. In the production of stainless steel wire of good fatigue resistance,the art'which comprises providing wire essentially consisting of about18% to 20% chromium, about 8% to 11% nickel, carbon not exceeding about.03%, and remainder substantially all iron; cold-drawing thesame,without benefit of intermediate anneal, in an amount exceeding 80% andon up to about 95%; and tempering at about 1615 F. to 1750 F., giving afine equi-axed grain structure.

8. In the production of stainless steel wire of about .006 to .013 inchdiameter and of good fatigue resistance,

the art which comprises providing wire essentially con-. sisting ofabout 17% to 19% chromium, about 8% to 10% nickel, about 08% to .20%carbon, and remainder substantially all iron; cold-drawing the same,without benefit of intermediate anneal, in an amount exceeding andtempering at about 1615 F. to 1750 F., giving a fine equi-axedgrainstructure.

9. A woven wire belt, the warp wires of which are of stainless steel ofabout .006 to Vs inch diameter and essentially consisting of about 16%to 26% chromium,

about 6% to 22% nickel, carbon not exceeding about 7 ;-.25%,-andremainder substantially all iron and having a uniform fine equi-axedgrain structure.

10. A woven wire belt, the warp wires of which are of stainless steelessentially consisting of about 16% to 18% chromium, about 10% to 14%nickel, about 2% to 3% molybdenum, carbon not exceeding about .03 andremainder substantially all iron and having a fine ,equi-axed grainstructure.

11. A woven wire belt having stainless steel warp wires of about .006 to.013 inch diameter and essentially con sisting of about 16% to 18%chromium, about 10% to 14% nickel, about 2% to 3% molybdenum, carbon notexceeding about 03%, and remainder substantially all iron, and having afine equi-axed grain structure; and having stainless steel shute wiresessentially consisting of about 17% to 19% chromium, about 10% to 13%nickel, carbon not exceeding about .12%, and remainder substantially alliron in the fully annealed condition.

12. In the production of stainless steel of good fatigue resistance, theart which comprises providing steel not exceeding /2" thickness andessentially consisting of about 16% to 26% chromium, about 6% to 22%nickel, carbon up to about .25% maximum, with remainder substantiallyall iron; cold-reducing the same, without benefit of intermediateanneal, in an amount exceeding about 80% and giving a tensile strengthof at least about 250,000 psi; and then tempering the same at atemperature of at least about 1200 F. for at least about 1 minute togive an elongation of at least about 20% with a tensile strength notexceeding about 140,000 p.s.i. and fine equi-axed grain structure.

13. In the production of stainless steel wire of good fatigueresistance, the art which comprises providing wire essentiallyconsisting of about 16% to 26% chromium, about 6% to 22% nickel, carbonup to about .25% maximum, with remainder substantially all iron;cold-reducing the same, Without benefit of intermediate anneal, inamount of about 80% to 95% reduction in area and giving a tensilestrength of at least about 250,000 p.s.i.; and then tempering the sameat a temperature of at least about 1400" F. to give an elongation of atleast about 18% with a tensile strength not exceeding about 150,000

psi. and with fine equi-axed grain structure.

14. In the production of stainless steel of good fatigue resistance, theart which comprises providing steel not exceeding /2" thickness andessentially consisting of about 16% to 26% chromium, about 6% to 22%nickel, carbon up to about .25 maximum, with remainder substantially alliron; cold-reducing the same, without benefit of intermediate anneal, inan amount exceeding about and giving a tensile strength of .at leastabout 250,000 p.s.i.; and then tempering the same at a temperature ofabout 1200 F. to 1900 F., with tempering at a temperature of at leastabout 1400 F. for a reduction of 82% or more and at least 1280 -F. for areduction of or more, giving a steel of at least 16% elongation and fineequiaxed grain structure.

15. In the production of stainless steel wire of good fatigueresistance, the art which comprises providing wire essentiallyconsisting of about 16% to 26% chromium, about 6% to 22% nickel, carbonup to about .25% maximum, with remainder substantially all iron;coldreducing the same, without benefit of intermediate anneal, in anamount of about 80% to reduction in area; and then tempering the same ata temperature of about 1400 F. to 1900 F., with tempering at about 1700F. to 1900 F. for reductions exceeding about 80%, and at about 1500 F.to 1900 F. for reductions exceeding about 90% to give steel of at least30% elongation and line equi-axe-d grain structure.

References Cited in the file of this patent UNITED STATES PATENTS2,088,449 Specht July 27, 1937 2,527,521 Bloom Oct. 31, 1950 2,578,782Campbell Dec. 18, 1951 2,590,074 Bloom Mar. 25, 1952 2,598,760 Cobb June3, 1952 2,686,116 Schernpp et al. Aug. 10, 1954 2,795,519 Angel ct alJune 11, 1957 2,815,273 Moore Dec. 3, 1957 2,851,233 Hayden Sept. 9,1958

1. IN THE PRODUCTION OF STAINLESS STEEL OF GOOD FATIGUE RESISTANCE, THEART WHICH COMPRISES PROVIDING STEEL NOT EXCEEDING 1/2" THICKNESS ANDESSENTIALLY CONSISTING OF ABOUT 16% TO 26% CHROMIUM, ABOUT 6% TO 22%NICKEL, CARBON UP TO ABOUT .25% MAXIMUM, WITH REMAINDER SUBSTANTIALLYALL IRON; COLD-REDUCING THE SAME, WITHOUT BENEFIT OF INTERMEDIATE ANNEALIN AN AMOUNT EXCEEDING ABOUT 80% AND GIVING A TENSILE STRENGTH OF ABOUT250,000 P.S.I. OR MORE; AND THEN TEMPERING THE SAME AT A TEMPERATURE OFABOUT 1200*F. TO 1750*F. FOR ABOUT 1/10 TO 30 MINUTES TO GIVE ANELONGATION OF ABOUT 20% TO 40% WITH A TENSILE STRENGTH OF ABOUT 110,000TO 140,000 P.S.I. AND FINE EQUI-AXED GRAIN STRUCTURE.